Habitat account - Forests


91C0 Caledonian forest  * Priority feature

Background to selection

Distribution of SACs/SCIs/cSACs with habitat 91C0 Caledonian forest.  Click image for enlarged map.
Distribution of SACs/SCIs/cSACs with habitat 91C0 Caledonian forest. Click image for enlarged map.

Description and ecological characteristics

 

Caledonian forest comprises relict, indigenous pine forests of Scots pine Pinus sylvestris var. scotica, and associated birch Betula spp. and juniper Juniperus communis woodlands of northern character. Self-sown stands naturally regenerated from stock of genuinely native local origin recorded in the Caledonian Pinewood Inventory (Forestry Commission 1998) are included in the Annex I type. It is usually found on strongly-leached, acidic podzols, and these soil conditions are reflected in the ground flora, which typically includes the dwarf shrubs heather Calluna vulgaris, bilberry Vaccinium myrtillus and cowberry V. vitis-idaea, wavy hair-grass Deschampsia flexuosa, and the bryophytes Dicranum scoparium, Hylocomium splendens, Pleurozium schreberi and Rhytidiadelphus loreus. This type of woodland is noted for several rare northern species, including creeping lady’s-tresses Goodyera repens, twinflower Linnaea borealis and the moss Ptilium crista-castrensis. Some stands support populations of notable bird species, such as western capercaillie Tetrao urogallus and Scottish crossbill Loxia scotica.

 

The majority of this habitat corresponds to NVC type W18 Pinus sylvestris – Hylocomium splendens woodland, but it also includes some birch-dominated stands of W17 Quercus petraea – Betula pubescens – Dicranum majus woodland and W4 Betula pubescens – Molinia caerulea woodland. Stands of W19 Juniperus communis ssp. communis – Oxalis acetosella woodland are included within this Annex I type where they occur within Pinus – Hylocomium woodlands; otherwise they are referable to Annex I type 5130 Juniperus communis formations on heaths or calcareous grasslands. Examples of P. sylvestris on bog may in certain circumstances be referable to Annex I type 91D0 Bog woodland.

 

Studies of the terpenes in the resin of pine shoots have shown that there are biochemical differences between different pinewoods that are an expression of genetic differences (Forrest 1982; Kinloch et al. 1986). These studies identified distinct biochemical regions, with considerable variation between the individual pinewoods. Within these regions there is further variation. The pinewoods of the North West zone, near Kinlochewe, and those of the South West zone around Fort William are the most genetically distinct groups. Differences between the other regions are less significant.

European status and distribution

 

Within the EU, Caledonian forest occurs only in Scotland, but it is part of the heathy pinewoods that extend across the Boreal region of northern Europe on impoverished acid sands and drier peaty soils. Scottish pinewoods represent genetically distinct oceanic variants of the type.

UK status and distribution Click to view UK distribution of this habitat

 

Caledonian forest occurs in the central and north-eastern Grampian mountains and in the northern and western Highlands of Scotland. It is estimated that over 25,000 ha of this habitat survives in Scotland (MacKenzie 1999). This is an increase on previous estimates to take account of recent regeneration.

Site selection rationale

 

Site selection has ensured that there is coverage of the full genetic and ecological variation of Caledonian forest within its geographical range. The sites selected include the largest in the UK, and represent over 85% of the total area of ancient Caledonian forest. The overall resource of the habitat includes a substantial area of recent regeneration from native seed, but which in many cases does not yet represent established woodland and so has not been a priority for selection.

 

Site selection has concentrated on the largest and most diverse examples of the remaining Caledonian forest resource that have good internal woodland structure and the capacity for regeneration. Where adjacent or neighbouring woodlands appear to be fragments of a formerly more extensive woodland, they have been linked together as complexes for the purposes of site selection. The essential feature of these complexes is that the individual woodlands, both large and small, form a coherent ecological unit by reducing isolation and providing the opportunity to restore the connections between wooded habitats. Selection has excluded very small, remnant woodlands with poor structure that are isolated from other woodlands and/or where there appear to be poor prospects for regeneration.


Site accounts

Amat Woods Highlands and Islands
Amat Woods complex includes two Caledonian forest areas, Amat Woods and Alladale Woods, which are representative of the North Central biochemical region. The complex has been selected to represent the northern variation of this geographically wide-ranging region. Although comprising only remnants of a formerly more extensive woodland, the pinewood area is still large. The soils are mainly acidic, although basic flushes are a feature of the wood.
Ardgour Pinewoods Highlands and Islands
Ardgour Pinewoods complex includes the principal Caledonian forest areas of northern Ardgour, including Cona Glen, Doire Mór, and Loch Shiel Woodlands. These represent the South West Zone. The pinewoods of this zone are considered to be genetically distinct from that elsewhere in Scotland. However, their origins are believed to be similar to those of the North West Zone, in that the woods may have recolonised from pinewood remnants that survived the Ice Age on the then west coast of Scotland. The pinewoods in this complex are the largest, most intact and most diverse remnants of semi-natural pinewood in their biochemical region. There is a rich flora of oceanic mosses and liverworts (including the nationally scarce Cephalozia catenulata and Plagiochila carringtonii) and a notable invertebrate fauna, including the rare beetle Boletophagus reticulatus and the rare chequered skipper butterfly Carterocephalus palaemon.
Ballochbuie North Eastern Scotland
This large intact Caledonian forest area is representative of the North East biochemical region. It is the second-largest pine woodland in the region. Although genetically representative of the North East region in which it occurs, ecologically it may be considered as part of the adjacent Cairngorms complex. The forest is dominated by even-aged mature pine, mostly aged between 150–300 years, with the typical pinewood vegetation types, and locally a juniper Juniperus shrub layer. Characteristic species, such as twinflower Linnaea borealis and serrated wintergreen Orthilia secunda occur in the field layer. The site also locally supports unusual herb-rich pinewood vegetation, similar to that seen at Mar Lodge in the Cairngorms. It is well-known for its important populations of northern birds which include capercaillie Tetrao urogallus and Scottish crossbill Loxia scotica. Areas of 91D0 Bog woodland are present within the forest. 4030 European dry heath is present locally within, and more extensively above, the forest, along with smaller areas of 7130 Blanket bog and 4010 Northern Atlantic wet heath.
Black Wood of Rannoch Eastern Scotland
Black Wood of Rannoch is the most extensive area of relict Caledonian forest remaining in Perthshire. It is representative of the South Central biochemical region and is the most southerly pinewood selected. The wood contains important communities of species characteristic of old pinewoods, particularly lichens and fungi, and supports a number of rare species, such as coralroot Corallorhiza trifida and serrated wintergreen Orthilia secunda. It also supports populations of Scottish crossbill Loxia scotica and capercaillie Tetrao urogallus.
Cairngorms Highlands and Islands, North Eastern Scotland
The Cairngorms complex, consisting of six individually large Caledonian forest areas, including Abernethy and North Rothiemurchus, represents the more ‘continental’ East Central biochemical region, typically with W18b Pinus sylvestrisHylocomium splendens woodland, Vaccinium spp. sub-community. This complex of woodlands is the most extensive area of native pinewood in the UK and comprises almost half the total area of ancient Caledonian forest in Scotland. In common with the rest of Scotland, the upper limits of the pine woodland are mostly artificially depressed by grazing, but a more natural tree-line occurs at 640 m on Creag Fhiachlach. This is the highest altitudinal limit of woodland in the UK, and consists of bushy stunted growth of Scots pine Pinus sylvestris admixed with juniper Juniperus communis of a similar stature. The pine woodland shows transitions to a wide range of other vegetation, including 91D0 Bog woodland on the forest mires. There are areas of unusual herb-rich pine woodland at Mar Lodge, similar to those described at Ballochbuie. This type of forest is of very restricted distribution in Scotland. The forest contains nationally important populations of capercaillie Tetrao urogallus, Scottish crossbill Loxia scotica and the osprey Pandion haliaetus.
Glen Tanar North Eastern Scotland
Glen Tanar is representative of the North East biochemical region. It is the largest Caledonian forest area in this region and is the third-largest pinewood in the UK. Although genetically part of the North East region, ecologically the site may be considered part of the adjacent Cairngorms complex. Unlike most pinewoods in Scotland, Glen Tanar retains a wide range of age-classes of trees, exhibiting active colonisation of open areas by young trees, and with significant areas of juniper Juniperus communis understorey. The site contains nationally important populations of capercaillie Tetrao urogallus and black grouse T. tetrix, and is probably the most important locality in Britain for Scottish crossbill Loxia scotica.
Kinveachy Forest Highlands and Islands
The pinewood of Kinveachy is one of the major tracts of remnant Caledonian forest in Strathspey and is the third-largest pinewood in the region. Although genetically part of the North East biochemical region, ecologically it may be considered part of the adjacent Cairngorms complex. The range of forest habitat present is important for several bird species, including capercaillie Tetrao urogallus, Scottish crossbill Loxia scotica and crested tit Parus cristatus. The site is characterised by dense stands of pine with extensive juniper Juniperus communis scrub and birch Betula and alder Alnus woodland, within a matrix of open moorland, providing an opportunity for the woodland to function naturally through regeneration onto open areas.
Loch Maree Complex Highlands and Islands
Loch Maree Complex comprises four Caledonian forest areas, and is representative of the North West Zone. The pinewoods in this region are considered to be genetically distinct from those elsewhere in Scotland, though their origins are believed to be similar to those of the South West Zone. Genetic variation is high and the woods have affinities with the pinewoods of Spain and southern France. Pollen records from peat bogs in the area suggest that these pines may be the descendants of trees which survived the last Ice Age somewhere off the present west coast of Scotland when sea level was much lower. Together, these woods show a strong oceanic influence and mostly fall within NVC type W18 Pinus sylvestrisHylocomium splendens woodland, sub-types W18d Sphagnum capillifolium/quinquefarium and W18e Scapania gracilis. The woodland at Beinn Eighe is scattered and of variable canopy structure and shows a mixed range of age groups. The diversity of Atlantic bryophytes is a major feature of the site, and several national rarities are present, including Daltonia splachnoides. The Loch Maree islands support one of the least-disturbed remnants of native pinewood in Scotland. In the wettest areas within the woodland there are small-scale examples of 91D0 Bog woodland. At Shieldaig there is the most westerly pinewood remnant in the UK and one of the most extensive blocks of woodland in this biochemical region.
Rhidorroch Woods Highlands and Islands
Rhidorroch Woods complex represents the North biochemical region and is part of a larger mosaic of woodland. Virtually the complete range of woodland types characteristic of the north-west Scottish Highlands is found here, centred on the unmodified Rhidorroch river system and interspersed with areas of heathland, peatland and semi-natural grassland. The diversity of the ground flora reflects the diversity of conditions. Species include serrated wintergreen Orthilia secunda and creeping lady’s-tresses Goodyera repens.
Strathglass Complex Highlands and Islands
The Caledonian forest areas in Strathglass Complex are representative of the North Central biochemical region and are intermediate in type between the western and eastern geographic variants. The individual woodlands within the complex are some of the largest remaining intact stands of native pinewood in Scotland. Glens Strathfarrar and Affric are the most important pinewoods in the UK for the epiphytic lichen communities they support. A number of nationally rare lichen species occur in the woods, including Bryoria furcellata and Pannaria ignobilis. Birds typical of Caledonian forest, including capercaillie Tetrao urogallus and Scottish crossbill Loxia scotica, are represented. Interspersed amongst the forest habitat, areas of wetter peatland with scattered pine 91D0 Bog woodland are found.

SACs/SCIs/cSACs where this Annex I habitat is a qualifying feature, but not a primary reason for site selection

Beinn Dearg Highlands and Islands
Ben Nevis Highlands and Islands
 

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